In 1858 the Marist Brothers came to Glasgow at the invitation of Bishop Murdoch. In 1863 they took charge of St Mary’s Boys’ School.
In 1865 there were 300 boys taught by two Marist Brothers and five pupil teachers. Brother John, Brother Austin and Brother James were head teachers from 1865 to 1869.
By 1870 there were 400 boys and a staff of eight. Pupil teachers were instructed by a master or mistress who conducted the apprentices through an approved course which lasted four or five years. The instructions were given either before or after school hours and the pupils also attended night school.